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Implementation of next-generation sequencing in forward genetic screens greatly accelerated gene discovery in species with larger genomes, including many crop plants. In barley, extensive mutant collections are available, however, the causative mutations for many of the genes remains largely unknown. Here we demonstrate how a combination of low-resolution genetic mapping, whole-genome resequencing and comparative functional analyses provides a promising path toward candidate identification of genes involved in plastid biology and/or photosynthesis, even if genes are located in recombination poor regions of the genome. As a proof of concept, we simulated the prediction of a candidate gene for the recently cloned variegation mutant albostrians (HvAST/HvCMF7) and adopted the approach for suggesting HvClpC1 as candidate gene for the yellow-green variegation mutant luteostrians. [ABSTRACT FROM AUTHOR]

The barley chloroplast mutator (cpm) is a nuclear gene mutant that induces a wide spectrum of cytoplasmically inherited chlorophyll deficiencies. Plastome instability of cpm seedlings was determined by identification of a particular landscape of polymorphisms that suggests failures in a plastome mismatch repair (MMR) protein. In Arabidopsis, MSH genes encode proteins that are in charge of mismatch repair and have anti-recombination activity. In this work, barley homologs of these genes were identified, and their sequences were analyzed in control and cpm mutant seedlings. A substitution, leading to a premature stop codon and a truncated MSH1 protein, was identified in the Msh1 gene of cpm plants. The relationship between this mutation and the presence of chlorophyll deficiencies was established in progenies from crosses and backcrosses. These results strongly suggest that the mutation identified in the Msh1 gene of the cpm mutant is responsible for the observed plastome instabilities. Interestingly, comparison of mutant phenotypes and molecular changes induced by the barley cpm mutant with those of Arabidopsis MSH1 mutants revealed marked differences. [ABSTRACT FROM AUTHOR]

Rotated Image with Maximum Average Power Spectrum (RIMAPS) is a new image characterization technique that was recently described as a valuable tool for the analysis and characterization of technical and biological surfaces. The objective of this work was to ascertain whether RIMAPS may be used to obtain a quantitative description of patterns of development displayed by roots in hydroponics. Visual observations on roots of wild-type barley (Hordeum vulgare L.) grown in hydroponics by the sandwich method showed, before their submergence, an erratic growth with windings and turnings, which after several days created a tangle of roots above the water surface. This intricate morphology is difficult to study without disturbing the root development. Hence, RIMAPS is introduced as an original method for the quantitative description of root axes distribution in a nondestructive way. Accordingly, patterns of root development were recorded by a digital camera. The Gaussian fitting of RIMAPS spectra resultant from digital images of roots were used to analyze, quantify, and compare differences in the pattern of root development observed between the wild type and a barley root mutant. Additionally, a parameter G was introduced that is obtained from the Gaussian curve and quantifies differences in angles displayed by root axes during their development with regard to the axial direction. [ABSTRACT FROM AUTHOR]

Cytoplasmic line 2 (CL2) is a chlorophyll mutant that was selected from a plastid mutator genotype in barley. The dynamics of greening and plastid development of CL2 first-leaf blade contrasts with that of monocots. Previous characterizations of CL2 suggested that this mutant has a delay of plastid gene translation during embryogenesis. We hypothesize that CL2 is a mutant in the infA gene, which encodes translation initiation factor I (IF I). Wild-type barley infA gene differs in some nucleotides from that in wheat, but the corresponding IF I proteins are identical. However, infA from CL2 carries a point mutation, which leads to an amino acid change in IFI residue 52. One CL2-1ike seedling selected from a new mutator pool also carries a point mutation in infA gene, this time leading to a change of the universally conserved amino acid residue 32. Both point mutations were T → C substitutions. We sequenced the complementary DNA of the infA transcripts from the wild type and CL2 and found that the mutation was conserved at the mRNA level. Results strongly suggest that CL2 and CL2-like are infA gene mutants, this being the first time that a mutant phenotype is attributed to infA gene in a higher plant. [ABSTRACT FROM AUTHOR]